> Stages de M2 > Liste des stages proposés pour l’année 2014-2015 > Divisions with or without centrosomes

Divisions with or without centrosomes

proposé par Marie-Hélène Verlhac , : Centre Interdisciplinaire de Recherche en Biologie (CIRB), Collège de France, UMRCNRS7241-INSERM-U1050

Projet de stage : Centrosomes are the major microtubule organising centers (MTOCs) of animal cells. They increase the efficiency of spindle assembly during cell division and through the nucleation of astral MTs influence spindle positioning. Defects in centrosome number are associated with a variety of diseases such as cancer or neuro-developmental disorders. Although almost all animal cells contain centrosomes, complete centrosome loss is a feature of oocytes, imposing unique modes of spindle assembly and positioning. In mouse oocytes, multiple acentriolar MTOCs cluster together to assemble a functional bipolar spindle. These acentrosomal spindles are asymmetrically positioned and can segregate chromosomes correctly. The mechanisms of MTOCs clustering in oocytes are shared by some cancer cells bearing extra centrosomes, allowing the building of bipolar spindles and keep dividing. In this project, done in collaboration with the group of Renata Basto (Curie Institute), we will investigate two fundamental questions : what are the mechanisms that regulate chromosome segregation and spindle morphogenesis and position in the absence of centrosomes in oocytes and what are the consequences of adding back centrosomes to these cells ? For this we will attempt to add centrioles back into oocytes, using a genetic approach (Plk4 overexpression during oogenesis) and assess the consequences on oocyte development. Preliminary experiments show that progression through meiosis in oocytes overexpressing PLk4 during follicle growth is perturbed. We will analyze in great detail how meiosis progression is perturbed, in particular we will test the hypothesis of the presence of merotelic attachments.

Techniques mises en œuvre par le stagiaire : Immunofluorescence, Spining Disk Live microscopy, Super resolution microscopy (3D-SIM)

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